Reaction of cellulosic fabric with dimethylformamide solution of a diisocyanate



United States Patent 3,490,861 REACTION OF CELLULOSIC FABRIC WITH DIMETHYLFORMAMIDE SOLUTION OF A DIISOCYANATE Gerald B. Verburg, Metairie, La., assiguor to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed June 14, 1967, Ser. No. 645,871 Int. Cl. D06m 13/40 U.S. 'Cl. 8-1162 2 Claims ABSTRACT OF THE DISCLOSURE This invention relates to the finishing of cellulosic textile fabrics. More particularly, this invention relates to the finishing of cellulosic textile fabrics whereby the fabric is given improved resistance to wrinkling or mussing. Also, this invention relates to the finishing of cellulosic textile fabrics whereby the tearing strength and abrasion resistance can be improved without significantly affecting the wrinkle recovery angles of the fabric.

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

An object of this invention is to provide a method for treating or finishing cellulosic textiles whereby the textile is rendered resistant to wrinkling or mussing during use and will have improved smooth drying properties after laundering. Furthermore, the cellulosic textiles so treated may be laundered by procedures normally used with untreated textiles of similar type, which procedures may in clude the use of hypochlorite bleaching agents and the use of acid sours in the rinse without suifering any deleterious effects because of the treatment or drastic loss of the properties imparted by the treatment. The use of bis(isocyanatocyclohexyl)methane imparts such properties to cotton fabrics and results in finishes which are stable to acidic souring, alkaline hydrolysis, hypochlorite bleaching, and repeated laundering. A further object of this invention is to provide a method for treating or finishing cellulosic textiles whereby the textile possesses improved tearing strength and abrasion resistance without significantly affecting the wrinkle recovery angles of the fabric when n-octadecylisocyanate is incorporated as a coreactant.

Because of their poor resiliency, cellulosic textile fabrics tend to become wrinkled in use and acquire a mussed or unpleasant appearance. To overcome this objectionable property, it has been the practice to treat or finish cellulosic textiles with the methylol derivatives of organic nitrogen compounds, such as urea, ethyleneurea, guanidine, melamine, and the like. These agents produce a finished cellulosic textile that has improved resistance to wrinkling or mussing while in use and give to the textile the ability to dry smooth after laundering. Textiles finished with many of these agents, however, cannot be bleached with the usual hypochlorite bleaching agents during laundering without the danger of suffering severe strength loss and discoloration. Also, the souring step common in many laundry procedures will often partially remove the finish produced by these agents and cause extensive loss of the imparted properties. These disadvantages are most pronounced with cotton textiles because of the more rigorous 3,490,861 Patented Jan. 20, 1970 laundry procedures to which cotton textiles are submitted as compared to those employed with other cellulosic or synthetic textiles.

The mechanism by which the agents mentioned produce the wrinkle resistance and smooth drying properties in cellulosic textiles is believed to be a crosslinking of the linear cellulosic molecules in the fibrous material. The effect can be accomplished by etherification of cellulose with the methylol compound using an acidic or alkaline catalyst. To obtain the necessary crosslinkage, the finishing agent must be polyfunctional, that is, contain two or more reactive methylol groups. The agents used, therefore, are di-, tri-, or tetramethylol compounds formed by the reaction of an organic nitrogen compound containing two or more nitrogen containing groups with formaldehyde in a ratio to give at least one molar equivalent of formaldehyde for each nitrogenous group. For example, the finishing agent dimethylol ethyleneurea is formed from the reaction of ethyleneurea with two molar equivalents of formaldehyde. Many of these nitrogenic agents, however, are damaged by bleaching during laundering.

The object of this invention may be accomplished by applying to the cellulosic fabric a diisocyanate, namely, bis(4-isocyanatocyclohexyl)methane in a dimethylformamide solution. The concentration of the diisocyanate to be used can vary between 6% and 50% of the solution. Acceptable crease recovery angles are obtained when a 6% concentration of bis(4-isocyanatocyclohexyl)methane is cured at 120 C. for 75 minutes. A 15% concentration of the diisocyanate appears to give the optimum performance, crease recovery angle of 277 (W-l-F). Even though increases in the crease recovery angle are obtained as the concentration of the diisocyanate is increased above 15 the changes above this concentration are small. However, increased concentration produced an advantageous increase in the tearing strength. The solution can be applied to the cellulosic fabric by wetting and padding. The wet fabric is then heated at 100 C.120 C. for 30 to 75 minutes. Adequate crease recovery angles are obtained at 100 C. for 75 minutes at 25% concentration. Improvement in the crease recovery angle occurs as the tempera- Y ture is increased from a crease recovery angle of 256 (W-l-F) at C. to 280 (W-l-F) at C. However, tearing strength decreases at the increased temperatures.

Satisfactory crease recovery angles of 282 (W-l-F) were obtained after 30 minutes at 120 C. and 25 concentration. No real advantage results from additional heating. In fact, additional heating has a detrimental effect on the tearing strength of the treated fabric. Acceptable crease recovery angles and improved tearing strength are obtained after 5-15 minute curing intervals, however a serious yellowing problem occurs at the shorter time intervals. The treated fabrics are then washed to remove any unreacted material. A nonionic detergent can be used during the wash. The fabrics are tumble dried and allowed to equilibrate under ambient conditions before evaluation.

In addition, treating or finishing cellulosic textiles with a bis(4-isocyanatocyclohexyl)methane in a dimethylf rmamide solution whereby n-octadecylisocyanate has been incorporated as a coreactant improves the tearing strength and abrasion resistance of the fabric without significantly aifecting wrinkle recovery angles. Fabrics treated in a his (4-isocyanatocyclohexyl methane dimethylformamide solution containing from l0%l5% n-octadecylisocyanate showed considerable improvement in tearing strength and abrasion resistance.

The properties of the cellulosic fabrics finished by the methods of this invention are illustrated in the following examples. All parts and percentages described are by weight. The degree of wrinkle resistance in the finished textile is shown by the crease recovery angle determined by the American Society for Testing Materials Test Dl42456T. The resistance of the textiles to hypochlorite bleach is shown by the strength retained in the American Association of Textile Chemists and Colorists Test 69- 1952. The tearing strength of the textiles is shown by the tearing strengths obtained by the Elmendorf method, American Society for Testing Materials Test Dl424 6T. Total chlorine is determined by the method of F. W. Cheng, Microchemical Journal, vol. 3, pp. 537-542 (1959).

EXAMPLE 1 A 6% dimethylformamide solution of bis(4-isocyanatocyclohexyl)methane was padded onto a sample of 80 x 80 cotton print cloth. The wet fabric was cured at original dimensions for 75 minutes at 120 C. The curing step was followed by a wash in hot water containing a nonionic detergent, a rinse in warm water and tumble drying. The treated fabric possessed a crease recovery angle of 250 (warp-l-filling) while an untreated, washed sam ple had a crease recovery angle of only 184 (warp+filling). The treated fabric had a tearing strength of 507 (g., warp) while an untreated, washed sample had a tearing strength of 820 (g., warp). The nitrogen content of the fabric increased 0.6% as a result of the treatment.

EXAMPLE 2 A 50% dimethylformamide solution of bis(4-isocyanatocyclohexyl)methane was padded onto a sample f 80 x 80 cotton print cloth. The wet fabric was cured at original dimensions for 75 minutes at 120 C. The curing step was followed by a wash in hot water containing a nonionic detergent, a rinse in warm water and tumble drying. The treated fabric possessed a crease recovery angle of 287 (warp-l-filling) While an untreated, washed sample had a crease recovery angle of only 184 (warp-l-filling). The treated fabric had a tearing strength of 494 (g., warp) while an untreated, washed sample had a tearing strength of 820 (g., warp). The nitrogen content of the fabric increased 1.3% as a result of the treatment.

EXAMPLE 3 A 25% dimethylformamide solution of bis(4-isocyanatocyclohexy1)methane was padded onto a sample f 80 x 80 cotton print cloth. The wet fabric was cured at original dimensions for 30 minutes at 120 C. The curing step was followed by a wash in hot water containing a nonionic detergent, a rinse in warm water and tumble drying. The treated fabric possessed a crease recovery angle of 282 (warp+filling) while an untreated, washed sample had a crease recovery angle of only 184 (warp-l-filling). The treated fabric had a tearing strength of 500 (g., warp) while an untreated, washed sample had a tearing strength of 820 (g., warp). The nitrogen content of the fabric increased 1.3% as a result of the treatment.

EXAMPLE 4 A 25% dimethylformamide solution of bis(4-isocyanatocyclohexyDmethane was padded onto a sample f 80 x 80 cotton print cloth. The wet fabric was cured at original dimensions for 75 minutes at 100 C. The curing step was followed by a wash in hot water containing a nonionic detergent, a rinse in warm water and tumble drying. The treated fabric possessed a crease recovery angle of 256 (warp-l-filling) while an untreated, washed sample had a crease recovery angle of only 184 (warp-l-filling). The treated fabric had a tearing strength of 513 (g., warp) while an untreated, washed sample had a tearing strength of 820 -(g., warp). The nitrogen content of the fabric increased 1.5% as a result of the treatment.

4 EXAMPLE 5 A 25% dimethylformamide solution of bis(4-isocyanatocyclohexyl)methane was padded onto a sample f 80 x 80 cotton print cloth. The wet fabric was cured at original dimensions for minutes at 120 C. The curing step was followed by a wash in hot water containing a nonionic detergent, a rinse in warm water and tumble drying. The treated fabric possessed a crease recovery angle of 280 (warp-l-filling) while an untreated, washed sample had a crease recovery angle of only 184 (warp+filling). The treated fabric had a tearing strength of 460 (g., warp) while an untreated, washed sample had a tearing strength of 820 (g., warp). The nitrogen content of the fabric increased 1.2% as a result of the treatment.

To demonstrate the properties of the above treatment on cellulosic fabric the following tests were carried out.

(1) A sample of x 80 cotton print cloth was treated as in Example 5. The treated fabric was cut in half and one-half was subjected to an acidic hydrolysis carried out at pH 2.02.5 for 40 minutes at 55i3 C. The crease recovery angle was 290 (warp+filling) before the acidic hydrolysis and 275 (warp-l-filling) after the hydrolysis. The percent nitrogen in the fabric did not change as a result of the hydrolysis.

(2) A sample of 80 x 80 cotton print cloth was treated as in Example 5. The treated fabric was cut in half and one-half was subjected to an alkaline hydrolysis carried out at pH 11 for 60 minutes at 80 C. The crease recovery angle was 285 (warp-l-filling) before the alkaline hydrolysis and 289 (warp-l-filling) after the hydrolysis. The percent nitrogen in the fabric did not change as a result of the treatment.

(3) A sample of 80 x 80 cotton print cloth was treated as in Example 5. The treated fabric was cut in half and one-half washed using the normal wash cycle with hot wash water and cold rinse water that contained 0.02% available chlorine and a nonionic detergent. After tumb-le dryin'g visual observation did not detect any discoloration. Analysis of the sample for total chlorine by the method of F. W. Cheng showed no pick up of chlorine by the treated fabric.

(4) A sample of 80 x 80 cotton print cloth was treated as in Example 5. The treated fabric retained of its strength after being subjected to the scorch test, Textile Chemists and Colorists Test 69-1952.

(5) A sample of 80 x 80 cotton print cloth was treated as in Example 5. The treated fabrics were Washed 4 times using the normal wash cycle with hot wash water containing a nonionic detergent and a cold rinse water. After each wash the fabrics were tumble dried for 35 minutes. When compared with treated samples having only the process wash the crease recovery angle was of the same magnitude (above 280 warp+filling), the tearing strength improved slightly (485 to 507 g., warp) and the percent nitrogen was virtually unchanged (1.3%).

EXAMPLE 6 A dimethylformamide solution containing 15% by weight of bis(l-isocyanatocyclohexyl)methane and 10% by weight of n-octadecylisooyanate was padded onto a sample of cotton print cloth. The wet fabric was cured at original dimensions for 75 minutes at 129 C. The curing step was followed by a wash in hot water containing a nonionic detergent, a rinse in warm water and tumble drying. Results are shown in Table 1.

EXAMPLE 7 A dimethylformamide solution containing 15 by weight of bis(4-isocyanatocyclohexyl)methane and 15 by weight of n-octadecylisocyanate was padded onto a sample of cotton print cloth. The wet fabric was cured at original dimensions for 75 minutes at C. The curing step was. followed by a wash in hot water containing a 6 nonionic detergent, a rinse in warm water and tumble tion containing about from 6% to 50% by weight of dr ing. Results are shown in Table 1. bis(4-isocyanatocyc1ohex l)methane,

(b) drying and curmg the treated fabnc for a perlod of TABLE 1 EFFECT ON THE PROPERTIES OF COTTON about minutes at a temperature of about 120 C.,

%gi tglgggg F liggvl g Afigglg g iglgi i -gggg- 5 (c) washing the fabric free of excess reagents. HEXYDMETHANE MIXTURE? A process for treating cellulosic textile fabrics comprising: Approxi $235. Tearing Abrasion (a) wetting the fabric with a 'dimethylformarnide so1um t add-0n angle Strength l'eslstarwe tlon containing about 15% by weight of b1s(4-1socy- Pad bath (percent) (degrees) (grams) (cycles) 10 anatocyclohexyDmethane and about from 10%- A by weight of n-octadecylisocyanate,

8 285 600 264 (b) drying and curing the treated fabric for a period of 1 -8 277 524 241 about minutes at a temperature of about C., The above data are average values of duplicate runs. The fabrics Washlng the fabnc fme of excess l'agentsl i i tii iii sili it t 1 th th th db 1 d 'th 01'1 rea e X CO 011 prm C O a a een 73.8 16 V1 B i li ii b t i t d r 257 b 4' t 1 h 1) th References Clted a a 1 6011515 8 O 3, IS "C 3 113 00 C 0 9X me C s glgtlgor in DMEt m N-diegh zrorm mide y 1 h D th UNITED STATES PATENTS e a a hconsis e 0 e15 is 4-isocyana ocyco exy me ane 10% n-oe1;adecylisoeyanate solution in DMF (N,N-dimethy1- 2,974,003 3/1961 Koemg 8 127'6 D ff g g t d f 157 bis. t 1 h 1) th 20 07, 11/1961 ams e a a COIISIS e 0 a ISOCYEAHEL ocyc 0 exy me me 15 78 ri-octadecylisocyanat solution in DMF (N,N-dimethy1- 3,350,163 10/1967 Mack et 8-4162 X ormaml e GEORGE F. LESMES, Primary Examiner I claim: I. CANNON, Assistant Examiner 1. A process for treating cellulosic textlle fabrics com- 25 prising: US. Cl. X.R.

(a) wetting the fabric with a dimethylformamide solu- 260209 

